1. Field of the Invention
The invention is directed to an actuation device for a friction clutch which is arranged in a drivetrain of a motor vehicle between a drive unit and a transmission in a housing, particularly in a housing bell or housing cover, and which includes a pressure medium force cylinder arrangement which is arranged in the housing and which preferably comprises a pressure medium force ring cylinder. The friction clutch can be actuated by means of this pressure medium force cylinder arrangement via a release bearing arrangement which is movable coaxial to the friction clutch. A measuring arrangement associated with the release bearing arrangement or a release bearing arrangement side of the pressure medium force cylinder arrangement or friction clutch detects an actual disengagement or release and has a plurality of measurement receivers arranged in the housing so as to be distributed about the clutch axis.
2. Description of the Related Art
Actuation devices of the type mentioned above are known, for example, from DE 197 16 600 A1 and U.S. Pat. No. 5,950,788, whose disclosure is incorporated herein by reference. In the known actuation devices, the measurement receivers are formed by hydraulic measurement cylinders. In order to prevent the hydraulic measurement cylinders from exerting any substantial tilting moments on the release bearing arrangement or release bearing arrangement side of the pressure medium force cylinder arrangement (especially a pneumatic force cylinder arrangement), U.S. Pat. No. 5,950,788 discloses constructing the hydraulic measurement cylinders (or, generally, a measurement receiver arrangement or transmitter element arrangement) essentially symmetric to the clutch axis. Especially in case of a plurality of hydraulic measurement cylinders, the cylinders are arranged so as to be distributed about the clutch axis at the same circumferential angle and at the same radial distance, so that transverse forces which are exerted by the individual measurement cylinders and which derive from the actual release compensate one another. Accordingly, on the whole, there is no substantial tilting moment acting on the release bearing arrangement or on the release bearing arrangement side of the pressure medium force cylinder arrangement (for example, a pneumatic ring piston). The risk of self-locking of the pressure medium force cylinder arrangement or pneumatic force cylinder arrangement is reliably prevented in this way.
The disadvantage in this kind of arrangement of hydraulic measurement cylinders (generally, measurement receivers) in the housing cover is in that the measurement receivers in the housing cover are hardly accessible, if at all, as long as the engine and transmission are connected, that is, while the drivetrain is not interrupted. In particular, it is not possible to remove or reinstallxe2x80x94possibly in the form of an exchangeable measurement sensor the measurement receivers for repair purposes or for exchanging a defective measurement receiver without disconnecting the drivetrain. However, disconnection of the drivetrain requires extensive disassembly and assembly and is consequently costly.
According to the invention, the actuation device is constructed in such a way thatxe2x80x94with a housing having at least one housing openingxe2x80x94at least several, preferably all, of the measurement receivers can be removed from the housing interior and reinstalledxe2x80x94possibly in the form of an exchangeable measurement sensorxe2x80x94through the at least one housing opening without disconnecting the drivetrain.
Conceivably, the housing (housing cover) could be constructed with a plurality of housing openings or a very large housing opening to enable removal and installation of the measurement receivers without disconnecting the drivetrain. However, this solution is disadvantageous insofar as the housing cover is weakened structurally by a corresponding quantity of housing openings or by a very large housing opening, which is not desirable especially for utility motor vehicles. Moreover, a plurality of housing openings are not always possible. Therefore, in a preferred further development a transporting device is provided by means of which at least one of the measurement receivers can be transported from an operating position farther from an associated housing opening to a disassembly or removal position closer to the associated housing opening. In this connection, at least one of the measurement receivers can preferably be transported by the transporting device from an installation position which is closer to an/the associated housing opening and which possibly corresponds to the removal position to the operating position which is farther from the associated housing opening. By the terms operating position and installation or removal position is meant, on the one hand, the position usually occupied by the measurement receivers during driving operation in order to detect the actual release and, on the other hand, a position to which the measurement receiver is transported by means of the transporting device and from which the measurement receiver can be removed from the housing through the associated housing opening, or a position occupied by the measurement receiver in the housing after installation before it is transported to its operating position for normal driving operation.
It may be advisable that a plurality of measurement receivers can be transported by means of the transporting devicexe2x80x94possibly successively in timexe2x80x94to a housing opening assigned jointly to these measurement receivers. A transporting device constructed in this way is advisable in particular when more than two measurement receivers are provided. A shared transporting device can then be provided for the measurement receivers.
There may be assigned to at least one measurement receiver an operating position in which the measurement receiver is associated with respect to position with a/the housing opening in such a way that it can be removed from the interior of the housing and can be installed againxe2x80x94possibly in the form of an exchangeable measurement sensorxe2x80x94without disconnecting the drivetrain. In this case, the operating position and the removal and installation positions coincide to a certain extent.
According to a preferred embodiment for the transporting device, it is suggested that this transporting device has at least one measurement receiver carrier which is movably mounted in the housing and which carries at least one measurement receiver and serves to transport the measurement receiver between an/the operating position which is farther from the housing opening and a/the removal or installation position which is nearer to the housing opening. In operation, the movably mounted measurement receiver carrier can also carry the measurement receiver which is removable from its operating position and is associated with the housing opening with respect to position. Alternatively, however, it is also possible that during operation the measurement receiver which is removable proceeding from its operating position and which is associated with the housing opening with respect to position is arranged at a measurement receiver carrier, preferably the pressure medium force ring cylinder, which is separate from the movably mounted measurement receiver carrier.
If it is desirable that a control/regulating valve arrangement which is associated with the pressure medium force cylinder arrangement and by means of which the pressure medium force cylinder arrangement can be actuated is arranged in comparatively close proximity to the pressure medium force cylinder arrangement, it may be advisable that the control/regulating valve arrangement is integrated in an actuation unit together with a measurement receiver. While it would be possible also to arrange the actuation unit in the housing so that it can be transported between an operating position and a removal and installation position by means of the transporting device, it seems particularly advisable to remove the actuation unit from its operating position and to reinstall it in this operating position. The measurement receiver which is integrated in the actuation unit can then be considered as a measurement receiver which can be removed proceeding from its operating position and which is associated with the housing opening with respect to position. This can be the only measurement receiver of this kind.
With respect to dependability of operation, it is advisable to fix the movably mounted measurement receiver carrier in position for operation by means of a positioning device. In this way, vibrations and the like cannot cause changes in position. Due to the fact that fixing in position could possibly be difficult to undo again, requiring the use of extensive force, for example, after a longer period of operation, it is suggested in a further development that a loosening device is provided in order at least to assist in loosening a measurement receiver carrier which is fixed in position.
To facilitate the installation and removal of the measurement receiver or measurement receivers, a drive device can be provided by means of which the movably mounted measurement receiver carrier is movable for transporting the at least one measurement receiver between its operating position and its removal or installation position. The drive device can advantageously have a toothed wheel gear unit which comprises, for example, a toothing formed at the measurement receiver carrier.
There are diverse possibilities with respect to the construction of the measurement receiver carrier. For example, the measurement receiver carrier can comprise a slide which is guided so as to be displaceable along a displacement path and which carries the at lest one measurement receiver. According to a particularly preferred variant, it is provided that the measurement receiver carrier comprises a rotating member or swiveling member which is mounted in the housing so as to be rotatable or swivelable, for example, a ring part or ring disk part surrounding the clutch axis. In this connection, it may be provided that the measurement receiver carrier is formed by the rotatably mounted pressure medium force ring cylinder or a carrying member arranged at the rotatably mounted pressure medium force cylinder.
According to another embodiment for the transporting device, the transporting device has at least one sliding guide in which at least one of the measurement receivers is guided in a displaceable manner between an/the operating position farther from the housing opening and a/the removal or installation position nearer to the housing opening. The sliding guide can comprise at least one elongated or link-like slot in a disk part arranged in the housing.
With regard to dependability of operation, it seems advisable that the measurement receiver can be fixed in the operating position. For example, the measurement receiver can be fixed by means of a fixing rod arrangement which can be supported at a supporting location which is stationary at least in operation, wherein the measurement receiver is held, for example, at a closed end of the sliding guide by means of this fixing rod arrangement.
The supporting location can be formed by a structural unit which contains a control/regulating valve arrangement by which the pressure medium force cylinder arrangement can be actuated. The structural unit can be arranged outside of the housing, for example, so that the valve arrangement is not subjected to the thermal influences occurring in the housing. With respect to the fixing rod arrangement, it is particularly preferable that it is formed by a line arrangement transmitting measurement signals from the measurement receiver to the structural unit. For instance, the line arrangement can be a hydraulic line arrangement which transmits measurement signals to the structural unit hydraulically, for example in the event that the measurement receivers are formed by hydraulic measurement cylinders. However, other line arrangements can also be considered, for example, an electric line arrangement, depending on the construction of the measurement receivers.
As was already indicated, the measurement receivers are preferably hydraulic measurement cylinders which are preferably arranged about the clutch axis in such a way that, in sum, essentially no tilting moment is exerted on a release bearing arrangement side of the pressure medium force cylinder arrangement by the measurement receivers. The measurement receivers are preferably arranged substantially symmetrically about the clutch axis.
In connection with the greatest possible structural strength of the housing, it is preferred that the housing has exactly one housing opening which is used for the installation and removal of the measurement receivers without disconnecting the drivetrain.
The invention is further directed to a motor vehicle drivetrain comprising a drive unit, a transmission and a friction clutch which is arranged between the drive unit and the transmission in a housing having at least one housing opening, and comprising an actuation device (preferably as described above), wherein at least several, preferably all, of the measurement receivers of this actuation device can be removed from the housing interior and reinstalled, possibly in the form of an exchangeable measurement sensor, without disconnecting the drivetrain.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.